Standalone mode and EV_USE_REALTIME

[Greg Hudson]

On Fri, 2011-09-09 at 04:45 -0400, Marc Lehmann wrote:
> EV_STANDALONE is documented to not rely on autoconfig, but instead on a
> manually provided configuration. It seems to me that if you want to avoid
> using realtime calls you can just define EV_USE_REALTIME to 0 in your
> custom config.
> 
> If this somehow doesn't work for you, then I'd be interested to hear why.

It works fine, and you're correct that EV_USE_REALTIME's default is
documented.  I was thrown off by this statement in the documentation:
        
        In standalone mode, libev will still try to automatically deduce
        the
        configuration, but has to be more conservative.

and by the fact that EV_USE_REALTIME's default is unaffected by
EV_FEATURE_OS.  It just seems a little incongruous to the other
deductions made by ev.c in standalone mode, which is why I asked whether
it was intended.

Also, the documentation of EV_USE_MONOTONIC has some text about needing
to link against librt, when this dependency appears to arise from
EV_USE_REALTIME, not EV_USE_MONOTONIC.

> clock_gettime is rather important for timekeeping purposes, so
> should be provided if possible.

I guess, but unless EV_USE_MONOTONIC is also deduced (which depends on
EV_FEATURE_OS and _POSIX_MONOTONIC_CLOCK in unistd.h), I think you wind
up with a dependency on librt for no benefit, per this text:

        This effectively replaces C<gettimeofday> by
        C<clock_get(CLOCK_REALTIME, ...)> and will not normally affect
        correctness.